Many herbicides have been used to secure quantities of crops harvested. Urea-series compounds, for example DCMU widely used as a herbicide for upland farms, have the defect that they cannot be used in paddies because of their strong phytotoxicity.
U.S. Pat. No. 3,332,975 discloses that m-chlorophenoxyureas which differ in chemical structure from the compounds of this invention can be used as medicines. As will be stated hereinafter, however, these compounds do not exhibit a herbicidal efficacy, and even if they do, their herbicidal efficacy is very weak.
Japanese Patent Publication No. 5254/1966 describes substituted ureas or thioureas represented by the following formula: ##STR1## wherein R.sub.1 represents a phenyl or halophenyl group, or a group of the formula ##STR2## in which R.sub.5 and R.sub.6 are the same alkyl or aralkyl groups, or may form a piperidino or morpholino group together with the nitrogen atom to which they are bonded; R.sub.2 represents a lower aliphatic hydrocarbon group, a phenyl group, or a phenyl group substituted by at least one of halogen, alkylmercapto, nitro and alkoxy; R.sub.3 and R.sub.4 are the same alkyl or aralkyl groups, or may form a piperidino or morpholino group together with the nitrogen atom to which they are bonded; and X is oxygen or sulfur.
It also describes that these compounds are herbicides, although it discloses no biological data.
Japanese Patent Publication No. 6999/1971 discloses that compounds of the following formula ##STR3## wherein R is a C.sub.1 -C.sub.4 alkyl group; Y is F, Cl, Br or I, a C.sub.1 -C.sub.4 alkyl group, or a C.sub.1 -C.sub.4 alkoxy group; n is 0, or an integer of 1 to 3 when Y is the halogen atom, or 1 when Y is the alkyl or alkoxy group; Z is F, Cl, Br or I or a C.sub.1 -C.sub.4 alkyl group; and a is 0, or an integer of 1 to 5 when Z is the halogen atom, or 1 when z is the alkyl group, are a herbicide to be applied to plants or their growing sites.
It is an object of this invention to provide novel substituted aryloxyureas.
Another object of this invention is to provide novel substituted aryloxyureas which exhibit an excellent herbicidal efficacy.
Still another object of this invention is to provide novel substituted aryloxyureas which exhibit an excellent herbicidal efficacy against weeds when applied to the weeds over a wide range of periods from a pre-emergence stage to a growing stage.
Yet another object of this invention is to provide novel substituted aryloxyureas which exhibit a herbicidal efficacy and yet are highly safe to crops or crop plants.
A further object of this invention is to produce the compounds of this invention having excellent herbicidal activity with industrial advantage.
Other objects and advantages of this invention will become apparent from the following description.